On Fri, Mar 29, 2024 at 03:30:11PM -0700, Andrii Nakryiko wrote:
> On Wed, Mar 27, 2024 at 3:21 AM Jiri Olsa <jolsa@xxxxxxxxxx> wrote:
> >
> > Add uretprobe syscall test that compares register values before
> > and after the uretprobe is hit. It also compares the register
> > values seen from attached bpf program.
> >
> > Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
> > ---
> > tools/include/linux/compiler.h | 4 +
> > .../selftests/bpf/prog_tests/uprobe_syscall.c | 163 ++++++++++++++++++
> > .../selftests/bpf/progs/uprobe_syscall.c | 15 ++
> > 3 files changed, 182 insertions(+)
> > create mode 100644 tools/testing/selftests/bpf/prog_tests/uprobe_syscall.c
> > create mode 100644 tools/testing/selftests/bpf/progs/uprobe_syscall.c
>
> [...]
>
> > +__naked unsigned long uprobe_syscall_arch_test(void)
> > +{
> > + asm volatile (
> > + "movq $0xdeadbeef, %rax\n"
> > + "ret\n"
> > + );
> > +}
> > +
> > +__naked void uprobe_syscall_arch(struct pt_regs *before, struct pt_regs *after)
>
> don't you get compiler warnings for using __naked with explicit
> function arguments?
nope, both gcc and clang are silent
>
> > +{
> > + asm volatile (
> > + "movq %r15, 0(%rdi)\n"
> > + "movq %r14, 8(%rdi)\n"
>
> [...]
>
> > + err = uprobe_syscall__attach(skel);
> > + if (!ASSERT_OK(err, "uprobe_syscall__attach"))
> > + goto cleanup;
> > +
> > + uprobe_syscall_arch(&before, &after);
>
> uprobe_syscall_arch() doesn't really do an explicit `syscall
> uretprobe`, it should work for int3-based uretprobes as well? Let's
> call it something a bit more generic then?
ok, how about
uprobe_syscall_arch -> uretprobe_regs
uprobe_syscall_arch_test -> uretprobe_regs_trigger
>
> Also, I think patch #1 will go through Masami's trace tree, right? But
> we can land selftests into bpf-next even before that, given they
> should work for both syscall and interrupt based uretprobes.
hm, not sure.. I did not originally cc Masami/Steven :-\ adding now
Masami, could patch 1 go through:
https://git.kernel.org/pub/scm/linux/kernel/git/trace/linux-trace.git
probes/for-next
thanks,
jirka
